The plasma processor is provided with at least: a processing chamber having a closed space and holding a substrate therein; a processing gas supply mechanism for supplying a processing gas into the processing chamber; an exhaust mechanism for reducing the pressure in the processing chamber; a high-frequency power supply unit for applying high-frequency power; and a plasma generating mechanism for, by the high-frequency power being applied by the high-frequency power supply unit, forming a plasma from the processing gas supplied into the processing chamber.
An example of the processing of a substrate using such a plasma processor includes an etching process. In an etching process, when, for example, fluorocarbon gas (CxFy gas) is used as a processing gas, polymers which are generated by forming a plasma from the fluorocarbon gas adhere to an inner surface of the processing chamber. The adhering amount of polymer varies depending on the temperature of the inner surface of the processing chamber. When the temperature is high, not much polymer adheres. When the temperature is low, much polymer adheres.
A flow rate of the fluorocarbon gas supplied into the processing chamber is regulated so as to be constant. Therefore, a small amount of polymer deposits on the substrate as a protective film when a large amount of polymer adheres to the inner surface of the processing chamber, and a large amount of polymer deposits on the substrate as a protective film when a small amount of polymer adheres to the inner surface of the processing chamber. Since there is a difference of the amount of the polymer depositing on the substrate between the two cases, it is not possible to perform etching efficiently. Further, it is also not possible to obtain a highly accurate etched shape. Hence, during the etching process, it is necessary to suppress a temperature rise of the inner surface of the processing chamber heated by the heat of the generated plasma to limit the temperature of the inner surface of the processing chamber within a certain range.
Conventionally, as a plasma processor capable of suppressing a temperature rise of an inner surface of a processing chamber, the plasma processor disclosed in Japanese Un-examined Patent Application Publication No. 9-275092 is suggested, for example. This plasma processor is configured to further comprise an inner member arranged at an distance from an inner peripheral surface of the processing chamber, two seal members which are arranged between an outer peripheral surface of the inner member and the inner peripheral surface of the processing chamber at a distance in the vertical direction from each other, and which form a closed space between them, and a cooling gas supply mechanism for supplying cooling gas into the space surrounded by the inner member, the processing chamber and the seal members in addition to the above-described configuration.
In this plasma processor, the cooling gas supply mechanism supplies cooling gas into the space surrounded by the inner member, the processing chamber and the seal members, and the inner member is cooled by the supplied cooling gas. Therefore, the temperature of the inner member is prevented from rising due to the heat of the generated plasma, and the temperature of the inner member is maintained within a certain range. Thereby, the amount of the polymer depositing on the substrate is stable, and the above-described disadvantage does not easily occur.
However, such a plasma processor also has the following problem. That is, since a certain time is required before the inner surface of the processing chamber (inner member) reaches a predetermined temperature by being heated by the heat of the generated plasma, it takes a certain time before the amount of the polymer depositing on the substrate is stabilized after starting the etching process. Therefore, the etching process is not stabilized until a predetermined time has elapsed after starting the etching process.
Therefore, a heater for heating the processing chamber (inner member) is provided in the plasma processor and the processing chamber (inner member) is heated by the heater in advance before starting the etching process to raise the temperature of the inner surface thereof to a predetermined temperature beforehand.
Patent document 1: Japanese Unexamined Patent Application Publication No. 9-275092.